import 'dart:io';

import 'package:flutter/services.dart';

import '../game/runtime_options.dart';
import 'game_package_manifest.dart';

class GamePackage {
  const GamePackage.asset({
    required this.rootPath,
    required this.manifest,
    this.runtimeLuaRoot = RuntimeOptions.defaultRuntimeLuaRoot,
  }) : source = GamePackageSource.asset;

  static const runtimeLuaPrefix = 'runtime:';

  const GamePackage.file({
    required this.rootPath,
    required this.manifest,
    this.runtimeLuaRoot = RuntimeOptions.defaultRuntimeLuaRoot,
  }) : source = GamePackageSource.file;

  final String rootPath;
  final GamePackageSource source;
  final GamePackageManifest manifest;
  final String runtimeLuaRoot;

  String get entryPath => _join(rootPath, manifest.entry);

  bool get isAsset => source == GamePackageSource.asset;

  Future<String> readText(String relativeOrAbsolutePath) async {
    final runtimePath = _resolveRuntimeLuaPath(relativeOrAbsolutePath);
    if (runtimePath != null) {
      return rootBundle.loadString(runtimePath);
    }

    final path = _resolvePackagePath(relativeOrAbsolutePath);
    if (isAsset) {
      return rootBundle.loadString(path);
    }
    return File(path).readAsString();
  }

  Future<ByteData> readBytes(String relativeOrAbsolutePath) async {
    final path = _resolvePackagePath(relativeOrAbsolutePath);
    if (isAsset) {
      return rootBundle.load(path);
    }
    final bytes = await File(path).readAsBytes();
    return ByteData.sublistView(bytes);
  }

  String resolveResourcePath(String keyOrPath) {
    final resource = manifest.resources[keyOrPath];
    if (resource != null) {
      return _join(rootPath, resource.path);
    }

    if (keyOrPath.startsWith(rootPath)) {
      return keyOrPath;
    }
    if (keyOrPath.contains('/')) {
      return _join(rootPath, keyOrPath);
    }
    return _join(_join(rootPath, manifest.assetsBase), keyOrPath);
  }

  String _resolvePackagePath(String relativeOrAbsolutePath) {
    if (relativeOrAbsolutePath.startsWith(rootPath)) {
      return relativeOrAbsolutePath;
    }
    return _join(rootPath, relativeOrAbsolutePath);
  }

  String? _resolveRuntimeLuaPath(String path) {
    if (!path.startsWith(runtimeLuaPrefix)) {
      return null;
    }
    final name = path.substring(runtimeLuaPrefix.length);
    if (name.isEmpty || name.contains('/') || name.contains('..')) {
      throw FormatException('Invalid runtime Lua module path: $path');
    }
    return _join(runtimeLuaRoot, name);
  }

  String _join(String left, String right) {
    final normalizedLeft = left.endsWith('/')
        ? left.substring(0, left.length - 1)
        : left;
    final normalizedRight = right.startsWith('/') ? right.substring(1) : right;
    return '$normalizedLeft/$normalizedRight';
  }
}

enum GamePackageSource { asset, file }